The present invention relates in general to heat reclaimers and, in particular to a new and useful heat reclaimer for extracting heat from the exhaust fumes of a heater such as a boiler or furnace.
The present invention is related to the inventions disclosed in the inventor's previous two patent applications which are incorporated here by reference. The first application entitled, Home Heating System, Ser. No. 946,188 filed Sept. 27, 1978 defines an overall system for enhancing the efficiency of heating units which may utilize a heat reclaimer such as the one disclosed in the present application. The other application entitled Balancing Air Device For a Heating Unit, Ser. No. 080,058 filed Sept. 28, 1979 defines a system for increasing the efficiency of a heating unit having a combustion chamber which system can be augmented and used in combination with the invention disclosed here.
Heat exchange devices are known for use in the exhaust flues of heaters such as furnaces and boilers. Some of these heat exchangers include tubes which are exposed to the exhaust fumes of the heater. A problem arises when the heat exchangers extract heat from the exhaust fumes to such a degree that the temperature of the fumes fluctuates through the ambient dew point. At this point some water vapor which is in the exhaust fumes condenses and may re-evaporate to form a steam blanket on the exterior of the tubes drastically reducing their heat transfer effect and also contributing to the deposit of soot thereon since the soot will adhere to the condensed fluid. This soot buildup also contributes to the possibility of a fire in the heat exchanger since, with sufficient amounts of soot deposited in the heat exchanger and at a sufficiently high temperature of the exhaust gases, the soot might be ignited. The water condensed in the heat exchanger may also cause corrosion and may even partially fill the device.
While high deposits of soot are usually the problem only in larger furnaces or boilers used for example in apartment houses and the like, smaller furnaces and boilers using heat exchange devices also experience problems connected with the condensation of vapors.